title: IL-6 does not predict current urolithiasis in stone formers.
abstract: BACKGROUND
  Interleukin-6 (IL-6), an inflammatory marker, has previously been found to be elevated in the urine of patients with urolithiasis. Oxalate and other stone precursors have been shown to increase IL-6 production in proximal tubular epithelial cells in vitro. We examined whether urinary IL-6 could be used as a screening test to determine current urolithiasis in individuals who are known to form urinary stones.
  
  
  METHODS
  Thirty-five adult patients with current urolithiasis demonstrated on imaging were enrolled in the study. Exclusion criteria included disease known to elevate IL-6. Each patient provided a pre-treatment urine specimen and one month after proven to be stone-free an additional urine specimen was obtained. The urinary IL-6/creatinine ratio was determined for both specimens and compared.
  
  
  RESULTS
  Ten patients provided both specimens. The mean pre-operative urinary IL-6/creatinine ratio before the procedure was 1.63 pg/mL. The mean post procedure urinary IL-6/creatinine ratio after the patient was confirmed to be stone-free was 1.81 pg/mL. These were not significantly different (p=0.38). Preoperative urinary IL-6/creatinine ratio did not correlate to stone size (r=0.15) and no correlation was seen between time from treatment and stone free IL-6/creatinine ratio (r=0.48).
  
  
  CONCLUSIONS
  Urinary IL-6 is not a good screening test for current urolithiasis in stone-forming individuals. It is elevated whether the stone is present or not.
authors.affiliation: Department of Urology, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California 90027, USA. Jocelyn.M.Rieder@kp.org
authors.forename: Jocelyn M
authors.initials: JM
authors.lastname: Rieder
authors.forename: Alan A
authors.initials: AA
authors.lastname: Nisbet
authors.forename: Timothy
authors.initials: T
authors.lastname: Lesser
authors.forename: Ethan I
authors.initials: EI
authors.lastname: Franke
authors.forename: John P
authors.initials: JP
authors.lastname: Brusky
authors.forename: Ashish R
authors.initials: AR
authors.lastname: Parekh
authors.forename: John
authors.initials: J
authors.lastname: Kaptein
authors.forename: Gary C
authors.initials: GC
authors.lastname: Bellman
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000652:urine*; D008297:Male; D008875:Middle Aged; D052878:Urolithiasis / Q000175:diagnosis* / Q000652:urine*
chemical_list: D015850:Interleukin-6